Chemistry 2e · 3.3 Molarity

Molarity: practice problems

12 problems from the book, with its answers. Check your working, or have any of them explained to you on the whiteboard.

1. Exercises 45

   What information is needed to calculate the molarity of a sulfuric acid solution?

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2. Exercises 47

   Determine the molarity for each of the following solutions:

   (a) 0.444 mol of CoCl₂ in 0.654 L of solution

   (b) 98.0 g of phosphoric acid, H₃PO₄, in 1.00 L of solution

   (c) 0.2074 g of calcium hydroxide, Ca(OH)₂, in 40.00 mL of solution

   (d) 10.5 kg of Na₂SO₄·10H₂O in 18.60 L of solution

   (e) 7.0 $\times$ 10⁻³ mol of I₂ in 100.0 mL of solution

   (f) 1.8 $\times$ 10⁴ mg of HCl in 0.075 L of solution

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3. Exercises 49

   Consider this question: What is the mass of the solute in 0.500 L of 0.30 M glucose, C₆H₁₂O₆, used for intravenous injection?

   (a) Outline the steps necessary to answer the question.

   (b) Answer the question.

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4. Exercises 51

   Calculate the number of moles and the mass of the solute in each of the following solutions:

   (a) 2.00 L of 18.5 M H₂SO₄, concentrated sulfuric acid

   (b) 100.0 mL of 3.8 $\times$ 10⁻⁶ M NaCN, the minimum lethal concentration of sodium cyanide in blood serum

   (c) 5.50 L of 13.3 M H₂CO, the formaldehyde used to “fix” tissue samples

   (d) 325 mL of 1.8 $\times$ 10⁻⁶ M FeSO₄, the minimum concentration of iron sulfate detectable by taste in drinking water

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5. Exercises 53

   Consider this question: What is the molarity of KMnO₄ in a solution of 0.0908 g of KMnO₄ in 0.500 L of solution?

   (a) Outline the steps necessary to answer the question.

   (b) Answer the question.

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6. Exercises 55

   Calculate the molarity of each of the following solutions:

   (a) 0.195 g of cholesterol, C₂₇H₄₆O, in 0.100 L of serum, the average concentration of cholesterol in human serum

   (b) 4.25 g of NH₃ in 0.500 L of solution, the concentration of NH₃ in household ammonia

   (c) 1.49 kg of isopropyl alcohol, C₃H₇OH, in 2.50 L of solution, the concentration of isopropyl alcohol in rubbing alcohol

   (d) 0.029 g of I₂ in 0.100 L of solution, the solubility of I₂ in water at 20 °C

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7. Exercises 57

   There is about 1.0 g of calcium, as Ca²⁺, in 1.0 L of milk. What is the molarity of Ca²⁺ in milk?

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8. Exercises 59

   If 0.1718 L of a 0.3556-M C₃H₇OH solution is diluted to a concentration of 0.1222 M, what is the volume of the resulting solution?

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9. Exercises 61

   What volume of a 0.33-M C₁₂H₂₂O₁₁ solution can be diluted to prepare 25 mL of a solution with a concentration of 0.025 M?

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10. Exercises 63

    What is the molarity of the diluted solution when each of the following solutions is diluted to the given final volume?

    (a) 1.00 L of a 0.250-M solution of Fe(NO₃)₃ is diluted to a final volume of 2.00 L

    (b) 0.5000 L of a 0.1222-M solution of C₃H₇OH is diluted to a final volume of 1.250 L

    (c) 2.35 L of a 0.350-M solution of H₃PO₄ is diluted to a final volume of 4.00 L

    (d) 22.50 mL of a 0.025-M solution of C₁₂H₂₂O₁₁ is diluted to 100.0 mL

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11. Exercises 65

    A 2.00-L bottle of a solution of concentrated HCl was purchased for the general chemistry laboratory. The solution contained 868.8 g of HCl. What is the molarity of the solution?

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12. Exercises 67

    What volume of a 0.20-M K₂SO₄ solution contains 57 g of K₂SO₄?

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